;; No JDBC driver lives in this sandbox, so the query runs over
;; data instead - and the parameters of an SQL query become the
;; arguments of an ordinary function
(def country-language
  [{:code "RUS" :language "Russian"   :percentage 86.6}
   {:code "RUS" :language "Tatar"     :percentage 3.2}
   {:code "RUS" :language "Ukrainian" :percentage 1.3}
   {:code "USA" :language "English"   :percentage 86.2}])

(defn languages-of [rows code min-percent]
  (->> rows
       (filter #(and (= code (:code %))
                     (> (:percentage %) min-percent)))
       (sort-by :percentage >)))

(doseq [r (languages-of country-language "RUS" 1.0)]
  (println (:language r) ":" (:percentage r)))

;; with next.jdbc the arguments simply follow the ? placeholders,
;; and the driver quotes them for you:
;; (jdbc/execute! conn ["select language, percentage
;;                       from countrylanguage
;;                       where code = ? and percentage > ?"
;;                      "RUS" 1.0])